Air-operated traffic counter

ABSTRACT

A traffic counter is actuated by the piston rod of an air motor, wherein pulses of air from an air hose across a roadway reciprocate the piston. Piston control and anti-bounce valves are provided in the air motor so as to prevent false counts.

United States Patent Trigg AIR-OPERATED TRAFFIC COUNTER [76] Inventor: Harry E. Trigg, 2013 Cunningham Dr,, Suite 102, Hampton, Va. 23366 [22] Filed: Aug. 27, 1973 21 App]. No.: 391,565

[52] US. Cl 235/99 A [51] Int. Cl. G06m l/08 [58] Field of Search 235/99 A, 99 R, 92 TC [56] References Cited UNITED STATES PATENTS Henkelman 235/99 A Sept. 17, 1974 12/1972 Trigg et all 235/99 A Primary ExaminerStephen J. Tomsky Attorney, Agent, or FirmJames H. Littlepage [57] ABSTRACT A traffic counter is actuated by the piston rod of an air motor, wherein pulses of air from an air hose across a roadway reciprocate the piston. Piston control and anti-bounce valves are provided in the air motor so as to prevent false counts.

3 Claims, 5 Drawing Figures AIR-OPERATED TRAFFIC COUNTER FIELD OF INVENTION Registers, Platform operated.

PRIOR ART Trigg US. Pat. No. 3,707,264.

OBJECTS I-Ieretofore, there have been devised traffic counters utilizing spring motors for driving a counter, wherein the motor was let off step-by-step, by pulses from an air hose (See Trigg, supra), and also there have been devised traffic counters wherein the counter was actuated step-by-step by an electric motor which, in turn, was energized through a switch which was closed by pneumatic pulses from an air hose. One of the problems in connection with these prior devices results from rapid pulsations produced typically by the wheels of two vehicles, side-by-side, passing over the air hose. These pulses may be only microseconds apart, and whatever mechanism there is that responds to them must be sensitive enough to respond and recover with utmost speed, but it must not be subject to reverberations or bounce. It is to this problem that the subject invention is directed.

More particularly, it is intended now to provide an air-actuated traffic counter which is driven step-by-step by the piston rod of a pneumatic motor whose piston is reciprocated by pneumatic pulses from an air hose stretched across a roadway. In order to permit the piston to advance and retract rapidly, check valves are provided at each end of the piston's cylinder, and in order to control the rate of advance and retraction, a needle valve is provided for throttling an opening through the cylinder wall.

These and other object will be apparent from the following specification and drawing, in which:

FIG. 1 is a perspective view showing the traffic counter in typical environment;

FIG. 2 is a plan view of the counter with the top of the casing removed;

FIG. 3 is a vertical cross-section through the counter;

FIG. 4 is a fragmentary cross-section along the lines 44 of FIG. 2; and,

FIG. 5 is a fragmentary cross-section along the line 5-5 of FIG. 3.

Referring now to the drawings, in which like reference numerals denote similar elements, the airoperated traffic counter 2 as shown in FIG. 1 in typical environment, wherein the air hose 4 therefore is stretched across a roadway and the counter is chained or otherwise suitably secured as at 8 to a tree 10 or a post. As shown best in FIGS. 2 and 3, counter 2 is contained within a casing 12 having a removable top 14 in which there are a window 16 for reading the count on counter 18 and an access door 20 through which the needle valve 22 on a piston motor 24 may be adjusted. Piston motor 24 and counter 18 are suitably supported on a bracket 26 within casing 12. The counter is actuated by a piston rod 28 having pivoted thereto as at 30 a link 32 which, in turn, is pivoted as at 33 to double pawl 34 which, upon oscillation about pivot 35, drives rachet 36 notch by notch. Ratchet 36 being on shaft 38 for counter 18 imposes a count upon counter 18 each time piston rod 28 advances. The piston 39 to which piston rod 28 is attached reciprocates back and forth in a cylinder 40 each time a pulse of air from air hose 4 is imposed upon it. In order to permit piston 39 to reciprocate within cylinder 40, a set of ports 42 is provided just forward of the retumed-position of piston 39, these ports 42 being controlled by flap valves 44 which function as check valves. In the head 46 of cylinder 40 are ports 48 which likewise are controlled by flap valves 50 which function as check valves.

Ordinarily, the aforementioned ports and flap valves would function as dash-pots, which militate against piston bounce and oscillation due to reverberation of air in hose 4. In order to control the speed at which piston 39 is permitted to travel, there is provided in the sidewall of cylinder 40 a port 52 which port is controlled by the aforementioned needle valve 22. The air input end of cylinder 40 is provided with a nipple over which air hose 4 is engaged, the latter passing through a suitable gromet 56 in the side wall of casing 12.

In operation, when the front wheels of a vehicle pass over air hose 4, the hose is compressed and a pulse of air drives piston 39 forwardly so that ratchet 36 is advanced one notch. As piston 39 starts to advance, all of flap valves 42 and 50 will be cracked open so that air escapes and some air, depending upon the setting of needle valve 32, will escape therethrough. As piston 39 advances forwardly, it closes ports 42 as it passes and coasts somewhat forwardly from ports 42. Before the rear wheels of the vehicle, or the wheels of another vehicle to the side of the first-mentioned vehicle can pass over the air hole, the latter returns from its compressed condition and sucks back piston 39 so as to advance pawl 36 another notch. On this return stroke, all the flap valves remain closed and the speed of the return stroke of the piston is governed primarily by the setting of needle valves 22 which permits air to be drawn in behind the returning piston. In practice, it has been found that by empirically adjusting needle valve 22, the piston motor and associated mechanism can be made to be bounce free and insensitive to reverberations of air in the air hose 4.

I claim:

1. An air-actuated traffic counter comprising a counter having an air hose adapted to be stretched across a roadway,

said counter having a drive shaft,

a ratchet on said drive shaft,

a pawl for driving said ratchet,

a piston motor having a piston and piston rod drivingly connected to said pawl and a cylinder having one end connected to said air hose,

said piston motor being responsive to the positive phase of an air pulse in said hose for advancing said piston to an advanced position and to the negative phase of said air pulse for retracting said piston to a retracted position, and valve means in said cylinder for controlling the rate of advance and retraction of said piston.

2. An air-actuated traffic counter as claimed in claim 1, said valve means including a port in the side wall of said cylinder and a needle valve for controlling the passage of air through said port.

3. In an air-actuated traffic counter as claimed in claim 2, port and outwardly-opening flap valve means therefor in that end of said cylinder towards which said piston advances, and port and outwardly-opening flap valve means therefor in the side wall of said cylinder forwardly of the retracted position of the piston. 

1. An air-actuated traffic counter comprising a counter having an air hose adapted to be stretched across a roadway, said counter having a drive shaft, a ratchet on said drive shaft, a pawl for driving said ratchet, a piston motor having a piston and piston rod drivingly connected to said pawl and a cylinder having one end connected to said air hose, said piston motor being responsive to the positive phase of an air pulse in said hose for advancing said piston to an advanced position and to the negative phase of said air pulse for retracting said piston to a retracted position, and valve means in said cylinder for controlling the rate of advance and retraction of said piston.
 2. An air-actuated traffic counter as claimed in claim 1, said valve means including a port in the side wall of said cylinder and a needle valve for controlling the passage of air through said port.
 3. In an air-actuated traffic counter as claimed in claim 2, port and outwardly-opening flap valve means therefor in that end of said cylinder towards which said piston advances, and port and outwardly-opening flap valve means therefor in the side wall of said cylinder forwardly of the retracted position of the piston. 